Apparatus for heat transfer by circulating water



May 6,1941. J. VAN VULPEN ,7

APPARATUS FOR HEAT TRANSFER BY QIRCULATING WATER 3 Sheets-Sheet 1 Filed March 2, 1940 6,, 1941- J. VAN VUL-PEN v APYARA-TUS FOR HEAT TRANSFER BY CIRCULATING .WATER Fiied da n 2, 1940 3 Shnets-Sheet 2 3- 0 O Q 0 O O 0' '0 y r J. VAN VULPEN 2,240,731

APPARATUS FOR HEAT TRANSFER BY CIRCULATING EATER Filed uar h 2, 1940 Y s Shse-tg-Sheet a mf Or i Dru 9 y;

Patented May '6, 1941 UNITED" STATES PATENT- OFFICE 4 arram'rus mL ng r-m as John Van Vulpen, Chicago, 111., assignor to Vapor Car Heating Company, Inc., Chicago, 111., a corno ation of New York Application March-2. 1940, Serial No. 321,848

2 Claims. (Cl. ear-s) This invention relates to certain new and useful improvements in apparatus for heat-transfer by means of circulating water, and more specifically to a means for maintaining desired temperature conditions within a space or series of spaces by circulating either hot or cold water through suitable radiators or heat transfer de-,

vices in these spaces, together with temperature responsive mechanism for controlling the circulation and temperature of the water or other liquid. This apparatus is specifically designed for heating or cooling the compartments or roome'ttes of a railwaypassenger car, although it will be obvious that the apparatus could be used for maintaining desired temperatures in other spaces.

Briefly described, the system or apparatus comprises a tank suitably supported, usually adjacent or beneath the floor oi the car, for containing the supply of water or other suitable heat-transfer liquid. Means are provided for heating this water to a desired-temperature and keeping it at this temperature; and preferably steam supplied from the pipe running longitudinally of the train from the locomotive is used ior this purpose. Other means may be provided for cooling the water supply during the summer season, or wherever and whenever refrigeration is required. A I

blowing means is provided for forcing air through van overhead conduit or conduits in contact with a radiator heat transfer device positioned in the conduit, and thence through discharge outlets into the several compartments. This radiator isincluded in a pipe loop extending from and back to the tank, this circuit also including a continuously operating pump for maintaining a circulation oi the liquid through the loop. A by-pass valve is also provided for shuntin 'the liquid flow from the supply to the return pipe of the loop without reaching or passing through the radiator at such times as the desired air-temperature has been established in the conduit. This lay-pass valve is thermostatically controlled to maintain a selected air temperature. A second pipe-loop extends irom'the tank through a plurality of the compartments, in series, and thence back-to the.

tank. A pump in this last mentioned loop malnwishes of the occupants of that particular compartment.

The principal object or this invention is to provide an improved heat-transfer apparatus oi-the type briefly described herelnabove and disclosed more in detail in the specifications which follow.

Another object is to provide improved means for maintaining the water in the supply tank at the necessary temperature for either heating or cooling, as the requirements maynecessi tate.

Another object is to provide improved means for automatically controlling the temperatureot the overhead air stream.

Another object is to provide improved means for controlling the circulation of the heated water through the floor radiators.

Other objects and advantages of this invention will be more apparent from the following detailed description or certain approved forms of apparatus constructed, assembled and operating according to the principles of this invention.

In the accompanying drawings:

Fig. 1 is a diagrammatic perspective showing the assembled apparatus in a car partially indicated in outline.

Fig. 2 is an elevation, partially broken away, showing a portion of one of the water circulating loops, and one of the compartment floor radiators and the supply and return connections hetween the loop and radiator.

cated in broken lines the end walls of one of the compartments or roomettes into which the railway car is divided. In the present example,

there are two rows of these roomettes. one ateither aided the central aisle, although it will I be understood that the car might comprise a single row oi compartments opening onto a side aisle. In fact, this invention, as to most 0! its ieatures. is adapted iorcontrolling the tempertains the circulationtat all times that any one oi the compartments requires heat. 'Ihereis a radiator in each compartment that is connected in shunt across a section of the loop-pipe so that a portion of the liquid flows through the radiator it a cutout valve at the is open. This valve is either manually or thermostatically controlled within thelcompartment to'malntain a selected temperature in accordance with the ature in any series of separated spaces. whether in a car or other structure, fixed or movable. It will be understood that. in actual practice the car will be much longer and there will be a great many more roometta than are here shown, a considerable portion or the car being broken away 7 and the grouping oi the apparatus condensed in order to show elements oi millc'lent size within the limited length of the drawings.

In the lower portion of each roomette, adjacent the floor .and one side wall thereof, is positioned a heating radiator A which will be hereinafter described more in detail, as well as the connections forsupplying hot water thereto. At some convenient location within the compartment or roomette is a switch B for manually'selecting the temperature to be maintained by radiator AL end by a duct ll in which are positioned a pain of similar radiators or heat-exchangers I 8-and IS. A blower or fan D' positioned in an air-feed chamber or duct 20 draws air'from within the car or from outside the car, or both, and forces this air in contact with the radiators I8 and I9 and thence through the ducts I5 and 15' from which the air is discharged through outlets l6 into the several compartments. The radiators l8 and I9 are supplied with properly heated or cooled liquid in the manner hereinafter described.

Supported at a suitable locationbn the car, usually adjacent or beneath the floor, and about midway the length of the car, is a supply tank E which holds that portion of the water supply not in circulation through the pipe systems, radiators, and heating and cooling mechanisms hereinafter referred to. 'While the liquid used is herein referred to and claimed as water, it will be understood that other suitable liquids could be used, and the water will usually con-- tain a suitable amount of anti-freeze solution so that no portion ofthe system will freeze up in cold weather.

While the water in the supply tank E and circulating systems may be heated in any suitable manner, ,an approved apparatus is herein disclosed whereby'steam is used,obtained from the main steam pipe 2 l which extends as usual from v the locomotive, or other suitable source of supply, throughout the length of the train. Steam flows from this main 2i through pipe 22 to the vapor regulator, indicated at 23. This vapor regulator, which is well known in the art, contains a valve which permits the flow of steam through pipe 24 and. distributing valve 25 until steam returns to the regulator through pipe 26, where upon the valve in the regulator is closed. When the electrically controlled distributing valve 25 is in closed or on position, the steam flow will be directed from pipe 24 through valveji and pipe 26 back to the vapor regulator. When valve 25 is in open position, the steam will flow through pipe 21 to and through the heat-exchanger, in-

dicated generally at 28,'and thence through pipe 29 back to the valve 25 and through pipe 28 to the vapor regulator. The heat-exchanger" is formed with a plurality of adjacent annular chambers or passages through one set of which this steam flows, and through another set of passages water from tank E flows so as to be heated by the condensing, steam. This water how is f 'from tank E through pipe ,30, T-fltting II and pipe 32 into one end of the connected water passages in the heat-exchanger 28, thence from the heat-exchanger through pipe 33, 1' 34 and pipe 35 into the other end of tank E. A pair of manually operated cut-off valves 36 are located in the pipes 32 and 33, these valves being open when the heating system is in operation, but closed when the cooling system, hereinafter described, is used. At 31 is indicated an aquastat of well known form, comprising a thermostat responsive to temperature changes of the liquid in the tank E and adapted to open and close the valve 25 so that the water in tank E will be-maintained at a predetermined temperature. Theelectrical connections between aquastat and valve 25, as well as all other electrical connections, are indicated in the wiring diagram of Fig. 5, hereinafter described. a

M; F is indicated a suitable refrigerating apparatus, for example, an ice-water sump or a mechanical refrigerating unit. One end of this refrigerating unit F is connected through pipe 38 with the T-fltting 3i, and the other end is connected through pipe 39 with the T-fitting 34, and cut-oil valves 40 are located in the respective pipes 38 and .39. -When the heating system is in operation valves 40 will be closed, but during the refrigerating season, valves 46 will be open and a pump G in pipe 39 will be continuously pered liquid from tank E to the overhead radia tors l8 and I9 comprises a pipe M extending from the tank E, a booster pump H, pipe 62, bypass valve J and pipe 53 to one end of the radiator or radiators i8 and i9, thence back through pipe 44, one-way valve and pipe 46 to the tank E. The pump H is continuously operating (when either the overhead heating or cooling systems are in operationhand when the by-paes valve J is in its open or on position the liquid flow will pass continuously to and through the radiators l8 and lfi'through the system already described. However, when the valve J is in its closed or "of! position, the circulating liquid will be shunted through pipe 41 from valve J directly back to pipe 46 and thence back to the tank E. The one-way valve It prevents how inthe opposition direction through pipe 48. It is simpler and more economical to let the pump H one of the air-conduits it which cooperate with suitable selecting means located in or on the panel indicated diagrammatically at L for-controlling the by-pass valve J. It will be understood that this panel L contains most of the relays and switches hereinafter shown and described in connection with Figs. 3 and 5, and

,this panel may be located at any suitable position in the car.

Hot water is supplied to the.fioor heat radisting system through the. outlet pipe 48 near one endlof tankE, thence through pipe 49 and T- fitting 50 through either or both of a pair of ,similar pipe loops M and N. thence through pipe 5|, pump 0 and pipe 52, back to the tank s. The

, loopQM comprises pipes 53, 54', 55, 56, balancing valve 51, and pipe 68 which leads into the pipe ll, already described. The other loop N may will causethe hotter water which flows onward through pipe II to flow out along the upper porportions of one or the other of the loops M and N in the manner hereinafterdescribed so that when any valve Pis open, a portion of the cir- 1 culating fluid will pass through the associated radiator A. As will be hereinafter shown in connection withv Fig. 5, whenever any one of the valves P is open, the pump will operate so as to maintain a circulation of hot water through the supply loop or loops, but when all of the valves, P are; closed, the pump 0 will cease oper-.

ating. The valves 51 and 51' are so adjusted as to balance the system, that is, so that the liquid flow will divide equally between the two loops.

M and N,

An air-cushion compression tank 59 is connected at 80 into the water circulation system. It will be understood that this tank containsan adequate volume of air which will be compressed by variations in the water pressure so as to provide a substantially constant and suitable pressure throughout the circulating system. Tank til may be provided with a suitable relief valve and air vent, indicated at 6 I Referring now more particularly to Fig. 2, it will be noted that each floor-radiator A comprises (in the present example) a pipe section 82 fitted with a plurality of radiating fins 63 to increase the heat-transfer surface A supply riser d extends upwardly from the pipe fitting 88 interposed in the main loop pipe 53 to the inlet v valve P which communicates with one end of the radiator A. The other end of the radiator is connected by a return riser 68 with another fitting M interposed in pipe 53'.

The solenoid valve P comprises a movable valve member 88 carried at the lower end ofvalve stem 89 and normally held down in closed position against valve seat 10 by the spring II. When the solenoid 12 is energized it will pull up the valve member against the resistance of the spring so as to open the valve passage leading to the radiaton The valve may also be moved to open position when desired, in case of failure of the electrical operating connections, by means of the cam 73 carried at the inner end of manually operable shaft 74 and engaging under the collar It on the movable valve member. The solenoid i2 is automaticallg operated to maintain a selected temperaturein the roometteiby means of the electrical connections hereinafter described in connection with Fig. 5.

A baiile member 18 fltted thin the pipe-fitting as is'provided with an inlet opening 11 of less diameter than that of pipe 53 so that a portion of the heated water stream will flow through opening l1 and continue through loop-pipe 88 while another portion of the heated water will be deflected upwardly through pipe 84 and thence to radiator A, all as indicated by the arrows in Fig. 2. Obviously this can only occur when valve P is open. At other times the only flow that can continue is that which proceeds outwardly through pipe 58. as shown by the lower arrow, at the lower lefthand side of Fig. 2. The internal fitting II at the other end ofthe radiator and within fitting 81 ispreferably reversed so that its outlet 18 is adjacent the top of pipe 83. This tion of the loop beyond the radiator, whereas the partially cooled water returned through riser 88 from radiator A will flow into the lower portion of the pipe loop. The baille connections within, fittings 85 and 81 are ofwell-known type and well suited for this purpose, but it will be understood that other types of dams pr baille'members could be used so as to shunt any desired portion of the water stream through the radiator A. The electrical control system will now be described, referring more particularly to Figs. 3, 4

and 5 of the drawings. The main control switch R (Fig. 3) is preferably-mounted in or on the panel L and comprises a casing 88 within which is mounted a plurality of switches I to I2 inclusive which are shown at various locations in switch, the individual switches l, 9, I0, II and' 'the wiring diagram of Fig. 5. These several switches are successively closed or opened, singly or in groups, by movement of the operating handle 8| on the face of casing 80, which handle is movable to seven different selective positions including one 0 'position, three heating positions and three cooling positions, all as indicated on the dial in Fig. 3. In the chart of Fig. 4, these several positions are indicated in the first vertical column, in horizontal alignment with which are twelve columns corresponding to the switches I to H2 inclusive; In each of these vertical columns where adot appears, this indicates that the corresponding switch is closed. For example, in the heating high position of the I2 are closed, whereas switches I to 8 inclusive and 8 are open. In the cooling low position, switches I, 2, 8 and ID are closed and all others are open. This switch R controls the selection of temperatures for the overhead heat or circulated air for both heating and cooling. The floor heat by means of radiator A is controlled by the individual switches B in the several compartments, as hereinafter described.

Referring now more particularly to Fig. 5, in the lower left hand portion of Ithis figure is indicated a fan-switch S, which is preferably located in the panel L,and which controls the fan or blower hereinabove referred to'and indicated at D in Fig, 1. The motor for this blower is also indicated by the reference characterD in Fig. 5. This fan-switch 8 comprises a pair of simultaneously movable arms or contacts 82 and 83, the

arm 82 .being movable into engagement with either of a pair of fixed contacts 84 and 85 so as to change the amount of selected resistance in the fan-motor circuit and-thereby provide two fan speeds, The circuit extends in an obvious manner from negative power main 86 through switch 8 and fan-motor D to the positive main 8!. At the same time the other arm 83 of switch 8 will be engaged with one or the other of. the" contacts 88, -thereby completing a circuit connection from the neg-ativepower main 88 to the ments and circuits, bracketed as X and X, re-

spectively. The similar elements in each-group are indicated byidentical reference characters. Each group represents the electrical control circuits and elements for one roomette or compartment of the car and although only two of these groups are shown in the drawings, it will be understood that there is a similar group of circuits for each of the several roomettes. A description of one group will sumce for all. Referring for the moment to Fig, 4, it will be noted thatswitches II and I 2 of the main control switch R tact t completes a short circuit around the recompletes. circuit from negative main 90 to positive main 9I so as-to energize the relay coil T. When relay T is energized, it serves to close each of the three movable contacts t, t and t" against the pairs of fixed contacts positioned adjacent thereto. When relay T is de-energized, the several movable contacts t, t' and t" will be raised to the position indicated in the drawings so as to break the circuits which they control. When a certain predetermined temperature is reached within the compartment, the mercury-tube thermostat C is adapted to complete a circuit through wire 92, the mercury column of the thermostat, and wire 93- so as to short-circuit the coil of relay T. Whenever the compartment temperature falls below this predetermined temperature,.'the mercury will fall so as to break 'this'shunt circuit and the relay T will immediately be energized. A heating coil 94 is closely associated with the thermostat C, this coil being energized through a circuit extending Irom'negative main ,90 through wires 92, 95, heating coil 94; wire 06, a portion of resistance 91 of the controlling switch B, wire-98, fixed resistances 09 and I00 and thence'to the positive main 9|. The amount of additional heat imparted by coil 04 will determine the temperature at'which the thermostat C will function to de-energize the relay T. For example, if the thermostat C is so designed as to function to close the shunt circuit therethrough at a room temperature of sistance I00 so that this amount of resistance will be temporarily out out of the heating circuit for heater 94. As a consequence a slightly greater'amount of heat-will be added to the thermostat C so as to anticipate or advance the temperature at which the supply of heating medium to radiator A will be cut off. In other words,-if

a temperature of 72 is desired in the roomette, the flow of hot water to the radiator may cut off at 71 since there is a lag in the heat transfer from radiator A to the air of the room and the heat already in the radiator will be added to the room temperature after the valve P is closed.

As soon as the shunt circuit through thermostat C has been completed, relay T will be de-energized and all of the contacts t, t and t" will be opened. Breaking the heating circuit at t will again add the resistance I00 to the heating circuit so as to reduce the auxiliary heat imparted by coil 94 and permit the thermostat C to again respond directly to the room temperature as selected by switch B. Breaking the solenoid switch at contact it will de-energize the solenoid l2 and permit valve P to close. Breaking the pump circuit at t would apparently stop the pump 0, but it will be noted that in each set of roomette controls there is a similar contact t" and all of these switches are connectedin parallel with one circuit will remain closed and the pump 0 will continue to operate. In the event that the temperature requirements are, for the time being,

satisfied in all of the roomettes or compartments,

then all of the contacts t" will be opened and the pump 0 will cease to operate. The overhead-heat controls will now be de-' scribed, referring more particularly to the cen- 75, if 5 0: additional heat are imparted to the thermostat by the coil 94, then the thermostat will'actually function at a room temperature of 10". 'It will now be apparent that if the selector switch B is adjusted to add to or subtract from the amount of resistance 91 that is effective in the circuit, there will be a consequent adjustment of the heating current in coil 84 and the exact temperature atwhich the thermostat will function will thus be selected. The dial on switch B may. be so calibrated as to indicate the room temperature that is selected.

Whenever the roomette temperature i'alls be: low the desired temperature, the shunt circuit through the thermostat will be broken and relay T will be energized so as to close the three movable contacts t, t and t". The contact t'f completes a circuit through the water-circulating pump 0, which circuit, It will be'noted, has al-.

pletes a circuit through the solenoid winding 12 '75 tral portion of Fig. 5. First it will be noted that (Fig. 4) when the main control switch R is moved to any one of the heating positions high;

.medium or low the switches I, 9 and I0 will all be closed. The closing of switch I0 will complete a circuit from negative main I03 to positive main I04f through the pump H which will run continuously as long as the overhead-heat system is in operation. The closing of switch 9 will complete a circuit through the relay U between mains 89 and 81, this relay controlling the by-pass valve J. The relay U includes a movable contact it which alternatively completes one or the other or two branches of a circuit that has been completed by'the closing of switch I.

the shunt circuit will be broken and relay U will be energized. This'will draw down the bridging contact u so as to connect the fixedcontacts I08 and I00 and a circuit will be completed from negative main IIO through movable contact III, solenoid coil "2, wires H3 and- ,II4, relay contacts I00, 14' and I09, and thence through closed switch I to the positive main H5.

about relay W and adapted to de-energize the The solenoid I I2 is a part of the operating mechanism for by-pass valve J and, when energized,

water will flow on through the overhead radiators I8 and I3 before returning to the supply 5 tank E. At the completion 01' this valve opera ating movement, the movable contact, member III will be moved ,up out of engagement with fixed contact IIS into engagement with another contact III, as indicated in dotted lines. Another solenoid II8 of the by-pass valve J is adapted to move the valve back toa position whereby the hot water will be by-passed through pipe 41 and will not reach the radiators I8 and I9. When the desired temperature has been reached within the roomette and a shunt circuit has been'completed through thermostat I05, the relay U will be tie-energized so that contact u will move back into engagement with a pair of fixed contacts H9 and I20, and it will be now apparent that another circuit will now be completed through solenoid II8 so as to operate the by-pass valve to the ofi" position. At the completion of this movement the switch arm III will be moved back to the original position shown in solid lines. The switch operating solenoids H2. and H8 require a rather heavy current, and if this current was permitted to flow for a protracted time the coils might be burned out. For this reason a thermally operated safety switch is indicated at IZI which will break this circuit in the event that the valve or operating mechanism sticks and the current flows too long. In this event a pilot light, indicated at l22,'wi11 throw additional resistance in the circuit and will give a it ng signal. 1 The relay indicated at W is normally cner gized through its circuit extending between the mains no and iI$.' A shunt circuit extending same may be completed through a switch 31' which is actuated by the aquastat 37 (Fig. 1) responsive to the temperature of the water supply in tank E. The distributing valve 23 (Fig. l) which controls the steam flow throughheat exchanger 28, is of well known type and comprises a pair of operating solenoids I23 and I2l adapted to move this valve to the ofi and on" positions, respectively. The relay W comprises a movable bridging contactv to which, when the relay is de-energized, will be in. the upper position now shown in the drawings so as to complete the ofi" circuit through solenoid I23. When re-' lay W is energized the contact 10 will be moved down so as to complete the on? circuit through the other solenoid I24. The operation of this portion of the mechanism is much the same as that of the Icy-pass valve J, already described.

A heating coil I25 is associated with thermostat IOS so as to lower the temperature at which the thermostat will iunction, this coil I25 being energized through a circuit having two branches. one of which includes the resistance I28 and switch 5 and the other of which includes a resistance I2? and switch 6. It will be noted that 65 if the main control switch R is moved to the heating low" position, then the switch 5 will be closed. This will result in a certain amount of that the function at a medium temperature. serves to move this valve so that the heated,

Referring now to Figs. 3 and 4 in connection with the lower portion of Fig; 5, it will be noted that when main control switch R is moved to any one of the three cooling positions the switches I, 3 and I0 will be closed. Switch III, as already noted, serves to close the energizing circuit for pump H which operates the same for either heating or cooling. The closing of switch I'serves to complete a circuit between mains 89 Land. 81 through the cooling pilot relay I28 and this relay closes the switch I23 completing an energizing circuit through the relay Y. The energization of relay Y serves to close a contact 11 which completes an energizing 'circuit between mains 86 and 81 for energizing the cold water circulating pump G (see also Fig. 1). The closing of switch I also completes an energizing circuit between mains 83 and 81 for the relay Z. This relay Z is adapted to control the bypass valve J during the cooling operations. The three thermostats I30, I! and I32 are positioned in shunt circuits extending around relay Z, these circuits being controlled respectively by the three switches 2, 3 and 4., It will be noted from Fig. 4 that when the main switch R. is moved to the cooling low" position, the switch 2 will be closed so that when thermostat I30 responds to a certain predetermined temperature within the, roomette a shunt circuit will be completed, de-energizing the relay Z.. In a similarmanner the switch 3 will be closed at a certain medium temperature to complete a circuit through relay I3I which functions at this medium temperature. Similarly switch 4 will be closed at the cooling high temperature so that thermostat I32 will be in control of the relay. The contacts I33 and I34 are adapted to be bridged in any suitable manner for testing purposes when the main switch is in the cooling high" position. When relay Z is deenergized, the movable contact 2 (see central portion of Fig. 5) will be in the upper position now shown so as to complete a circuit through the operating solenoid II2 oi the by-pass switch J and move this switch to the on position. When the relayz is energized, the contact 2 will be moved down so as to complete an'energizing circuit for solenoid H8 and movethe switch to the 011" position. It will be noted that the switch 8 is in both of these circuits and will be closed, as already noted, when the main selector switch R is many of the cooling positions. It will be noted that the by-pass valve J is operated in the same manner as for heating with the exception that the movements are reversed. Obviously, when a certain high temperature is reached within the roomette it will be desirable to turn the heat oil during the heating season, but during the cooling season the cooling apparatus is turned on when a certain maximum temperature is reached. Many of the wires and resistances shown in Fig. 5 have not been specifically rei'erred to, but it is believed that their purpose will be obvious. Many variations might be made in the wiring system hereinabove shown and described, the one here disclosed by way of example being suitable for the purpose.

It will be noted that no overhead heating or cooling is possible unless the fan D is operating,

since the switch S must be closed in order to com-- plete a circuit through the negative main 8! from which power is obtained for an or the cooling control circuits, and also for the controlling relay U of the overhead heating circuits. However, if

the switch R is'moved to the "o position so that I in any of the cooling" positions or the floor-heat will not be operable since at this time the switches I and I2 will be open and the circuit for energizing the main controlling relay '1', and for energizing the pump 0 cannot be completed.

I claim:

1. In a means for heating a plurality of compartments by means of hot water, a supply tank, means for maintaining the water in the tank at a predetermined temperature, a pipe loop leading from the tank through the several compartments in series and back to the tank, a motor-driven pump in said loop for enforcing a circulation of heated water through the loop and tank, a plurality of radiators one in each compartment, a pair of riser pipes for each radiator connecting the respective ends of the radiator with the pipe loop at spaced apart locations, a plurality of cutofl valves one for each radiator and located in one of said pair of risers, means in said pipe connections for causing a portion of the circulating any one of the valves is open but stopping the I pump when all valves are closed.

2. In a means for heating a plurality of compartments by means of hot water, a supply tank, means for maintaining the water in the tank at a predetermined temperature, a pipe loop leading from the tank through the several compartments in series and back to the tank, a motor-driven pump in said loop for enforcing a circulation of heated water through the loop and tank, a plurality of radiators one ,in each compartment, a pair of riser pipes for each radiator connecting the respective ends of the radiator with the pipe loop at spaced apart locations, a plurality of cutof! valves one for each radiator and located in one of said pair of risers, means in said pipe connections for causing a portion of the circulating liquid stream to be shunted through a radiator when its respective valve is open, electrically actuated, thermostatically controlled means in each compartment for opening and closing the radiator valve to maintain a selected temperature in the compartment, said electrically actuated means serving to cause the pump to operate when any valve is open but stoppingthe pump when all valves are closed.

JOHN VAN VULPEN. 

